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Could my i5 2500 be bottlenecking my 2x 6970s in BF3?

Last response: in Graphics & Displays
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March 31, 2012 1:30:45 AM

I am having issues on higher settings (anything over medium with any aa) playing bf3 on an eyefinity setup (5760x1200).

In trying to pinpoint my bottleneck, I ran into some contradicting information.

But first my setup:
GPU: 2x AMD Radeon 6970 2GB
CPU: Core i5 2500 (stock cooler, no OC)
MB: Asus P8P67 Pro
8GB RAM
Running BF3 off of my 60GB SSD (also my boot drive). This has 15GB of free space.

So the first thing I did was use BF3's in game performance graph to check whether my CPU or GPU had a higher render time per frame:

(higher = worse):

Note that although this was taken at ultra settings at about 4500x1200 (windowed mode), this result held at every graphics level, and at every resolution. (The CPU always appeared to be holding back the GPU).

I'm also curious if the strange pattern on my GPU line means anything? It is flat except for frequent dips downward, always to the same point.

So this chart would indicate that my CPU is the problem; however, because this was in windowed mode, I was watching my CPU usage at the same time, with the following results:


And I think the above indicates that my CPU is not being taxed all that much (and additionally confirms that RAM is not the issue).

Finally I ran GPU-Z to determine if my graphics card was the problem with the following results:

This seems to indicate that even at ultra settings, the GPU is not at max load (only 82%).

I am also struggling to make sense of the VRAM results. VRAM was over capacity (is this possible?) at ultra settings; however this was not the case for many of the other settings levels I tested. Even at the lower settings levels where VRAM was not an issue, the CPU was slower according to the in game performance graph, but also not struggling according to the CPU usage graphs.

Basically I have contradicting results from 3 different places and no idea what to believe.

TL;DR: Based on contradicting evidence from above pics, could be either my CPU or or my GPUs.

Could anyone here make more sense of this than I can? I am trying to figure out whether to sell off my 6970s for some 680s or to get a better unlocked processor, a cooler, and overclock it.
a c 88 U Graphics card
a b à CPUs
March 31, 2012 1:38:22 AM

Nothing wrong with considering an upgrade with the set up and resolutions you are running , you could sell off the 6970's and go for 680's or 7970's, but I would firstly suggest an overclock of your 2500K and checking your ram usage whilst playing BF3 to see if it is topping out. With a set up like that the cpu needs to give your set up more juice and an overclock might just do the trick.
a b U Graphics card
March 31, 2012 1:42:52 AM

xitsej said:
I am also struggling to make sense of the VRAM results. VRAM was over capacity (is this possible?) at ultra settings; however this was not the case for many of the other settings levels I tested. Even at the lower settings levels where VRAM was not an issue, the CPU was slower according to the in game performance graph, but also not struggling according to the CPU usage graphs.


Your GPU can buffer things in unused system RAM as if it were a page file if it needs to and this displays as VRAM.
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a b U Graphics card
March 31, 2012 1:46:32 AM

First off, why are you not shooting your gun and taking the objective?!
March 31, 2012 1:51:46 AM

You could always overclcok your i5 before buying the futur ivy-bridge especialy since they seem to delay the release date every months. An OC i5-2500k is more then enough for your 3 monitor gaming needs. And I wouldn't upgrade to the 680gtx or the hd7970 if I was you. Since you already have two 6970 the cheapest way is to buy a third one will increase your speed and remove the microstuttering seen on 2x CF/SLI set-up.
a b U Graphics card
March 31, 2012 1:54:24 AM

In addition to what monsta said, make sure you have the latest AMD drivers (12.3) and CrossFire profiles installed. BF3 is a relatively new game and I know AMD has issued some performance tweaks since its release. I doubt it's a CPU bottleneck though. My guess is that you're bottlenecked by your VRAM. Remember that with CrossFire and 2x2GB cards you only get 2GB of VRAM not 4GB. You may well be maxing that out (GPU-Z seems to indicate this) with such a high resolution at Ultra settings. You are probably going to want cards with at least 3 GB of VRAM to play ultra on such high resolution.
a b U Graphics card
March 31, 2012 1:58:52 AM

nbelote said:
Your GPU can buffer things in unused system RAM as if it were a page file if it needs to and this displays as VRAM.


Correct, but remember the bandwidth limitations of PCI-E. Even though they seem high, they're no where near how much bandwidth the card needs for real time processing. Think 8GB/s for PCI-E 2.0 x16 vs. over 150 GB/s for most modern high end GPUs from VRAM. It's fine if it only occurs a few times, but if the driver is constantly swapping data back and forth over the PCI-E bus, it's going to be slow or stutter.
March 31, 2012 2:01:22 AM

aicom said:
In addition to what monsta said, make sure you have the latest AMD drivers (12.3) and CrossFire profiles installed. BF3 is a relatively new game and I know AMD has issued some performance tweaks since its release. I doubt it's a CPU bottleneck though. My guess is that you're bottlenecked by your VRAM. Remember that with CrossFire and 2x2GB cards you only get 2GB of VRAM not 4GB. You may well be maxing that out (GPU-Z seems to indicate this) with such a high resolution at Ultra settings. You are probably going to want cards with at least 3 GB of VRAM to play ultra on such high resolution.


Below Ultra 2gb of Vram should be enough and a few poeple claim that ultra only take 1.8G of Vram but I wouldn't trust this without proof ot back it.

http://www.youtube.com/watch?v=Kn8f_ZlTDMI
a b U Graphics card
March 31, 2012 2:10:26 AM

venur said:
Below Ultra 2gb of Vram should be enough and a few poeple claim that ultra only take 1.8G of Vram but I wouldn't trust this without proof ot back it.

http://www.youtube.com/watch?v=Kn8f_ZlTDMI


Agreed, now it's looking more like a driver issue again.

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March 31, 2012 2:19:24 AM
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aicom said:
Agreed, now it's looking more like a driver issue again.


Also: http://media.bestofmicro.com/X/L/320025/original/BF3%20...

This test was ran on a i5-2500k but I can't remember if it was OC or not (pretty sure it wasn't).

As you probably know two 6970s > 6990 so assuming everything is all right you shouldn't have any problem to run the game on high setting if a 6990 could run it at ultra with a min FPS of 35.
March 31, 2012 2:54:49 AM

venur said:
Also: http://media.bestofmicro.com/X/L/320025/original/BF3%20...

This test was ran on a i5-2500k but I can't remember if it was OC or not (pretty sure it wasn't).

As you probably know two 6970s > 6990 so assuming everything is all right you shouldn't have any problem to run the game on high setting if a 6990 could run it at ultra with a min FPS of 35.


Yeah now I have no idea whats going on. I just took this screen shot:


As you can see the VRAM is well below the 2GB limit. Its on high settings.
My FPS was 23 in this picture.

Could it be the temperature?
March 31, 2012 2:56:01 AM

i suggest the following :

lower the settings try the game if u get the same result its ur cpu or overclock ur cpu and try the game on the same settings if its better its ur cpu .... and ofc if u get the opposite results then its ur gpu's ... simple

a b U Graphics card
March 31, 2012 2:58:28 AM

OP: What version of AMD's drivers are you running?
March 31, 2012 3:26:43 AM

aicom said:
OP: What version of AMD's drivers are you running?


I just downloaded Catalyst Software suite 12.3 a few days ago. This includes the latest display drivers.
March 31, 2012 4:25:30 PM

Best answer selected by xitsej.
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